Control apparatus



May 30, 1950 A. J. SIEL-.SKI

comm. Apmwrus 5 Shots-Sheet 1 Filed April 30, 1947 5 Sheets-Sheet 2 7b/M attorney A. J. BIELSKI CONTROL APPARATUS vll May 3o, 195o Filed April 30, 1947 May 30, 1950 A. J. BlELsKl CONTROL APPARATUS 5 Sheets-Sheet I5 Filed April 5o, 1947 WMM May 30, 1950 A. J. BIELSK! 2,509,471

CONTROL APPARATUS Filed April C50, 1947 5 Sheets-Sheet 4 1 @Homey May 30, 1950 A. J. BIELsKl comox. APPARATUS Y Filed April 30, 1947 5 Sheets-Sheet 5 ttorlleg Patented May 30, 1950 CONTROL APPARATUS Alexander J. Bielski, Minneapolis, Minn., assigner to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application April 30, 1947, Serial No. 744,956

l 19 Claims.

The present invention relates to a fail safe step controller for electric house heating control.

In controlling relatively large electric currents, as in house heating, it is not only desirable to control the current in steps or increments to meet power company requirements and for nicety of heat control but it is essential that, upon a power failure or limit switch action, the load be immediately removed from the line and restored only by steps or increments with an appreciable time delay between said steps or increments. This feature of immediately disconnecting the load from the supply line upon power failure or limit switch action and permitting restoring of the load only by the predetermined steps or increments is commonly termed fail safe and obviously has the purpose of preventing overloading of the power supply line after power stoppages, limit switch action, or the like. It is therefore a principal object of this invention to provide an improved step controller having fail safe characteristics.

It is a further object to provide an improved and simplified step controller which is positive and dependable in operation and which cannot be placed in operation until the motor of the controller is in a predetermined initial operative position.

It is another object to provide a control device It is also an object to provide a controller operable by a heat motor and having a follow-up means driven by a shaft of the controller.

It is an additional object to provide a controller having improved switch mounting means.

It is a further object to provide a multiple switch controller having a terminal block and a fuse block superimposed thereon and having lmproved electrical connections therebetween.

It is another object to provide a control system for an electrical heating system wherein the heating currents are controlled by steps or increments and wherein the entire load is immediately disconnected upon a circuit failure or due to the overheating of the heating system.

It is a further object to provide a heat motor actuated device having follow-up means operated in response to the operation of the device and including a relay jointly operable by said follow-up means and a controller.

It is a further object to provide a cam operated switch carrier wherein said switch carrier can be positively operated in either direction but cannot be accidently moved in either direction.

These and other objects will become apparent upon a study of the following specification and drawings wherein:

Figure 1 is a side elevation of the present step controller, with parts broken away and parts in sections.

Figure 2 is a cross section taken on the line 2-2 of Figure 1.

Figure 3 is a cross section taken on the line 3 3 of Figure 1.

Figure 4 is a cross section taken on the same line as 3-3 of Figure 1 but viewed in a reverse direction as indicated by the numerals 4--4.

Figure 5 is a horizontal section of the heat motor seen in part in Figures 2 and 4.

Figure 6 is a plan View of a portion of the present controller showing the arrangement of some of the parts.

Figure 7 is a schematic connection diagram of the present apparatus.

Referring to the drawings, chassis IIJ forms a framework in and on which is mounted the apparatus comprising the present step controller. A switch shaft II is xedly attached to an end plate (not shown) and a partition I2 of chassis I Il, the several load switches of the controller being pivotally mounted along this shaft. The load switches, of the mercury type and of which I3, I4 and I5 are examples, are carried by mounting clips I8 attached to follower member I6.

Each follower member I6 includes a base portion I1 to which is attached a switch clip I8 and further includes side wall portions 2U and 2I bent up from the base I'I. Wall portion 20 is extended upwardly near one end to form a cam follower portion 22, and wall portion 2I is similarly constructed to form a cam follower portion 23 offset from portion 22 (Figs. 1 and 2). In addition, tongues 24 are bent inwardly from side wall 20 at each end of the same and tongues 25 are likewise bent inwardly from side wall 2I, tongues 24 and 25 being proportioned and arranged so that they, in conjunction with base II, form a groove for locating or guiding follower member I6 on shaft II. A bolt 2l extending through a spacer 28 maintains the side walls 20 and 2I in correct position and the spacer 28 rides in circumferential groove 29 in shaft II to locate each member I6 in its proper spaced relation along said shaft. A light spring 38 may be used between shaft and base |1 of member I6 to take up any unnecessary clearance between the member and the shaft. Thus, due to the coaction of base I1 and spring 38, tongues 24 and 25 and spacer 28 with shaft each follower member I6 is free to rotate on the shaft but cannot tip or tilt in a direction other than desired and cannot slip along shaft due to the aforementioned coaction of spacer 28 with circumferential groove 29.

A cam shaft 33 is rotatably mounted a short distance above and parallel to shaft II and carries a plurality of cam assemblies 36 each arranged for coaction with follower portions 22 and 23 of member I6. Cams 31 and 38 of an assembly 36 are generally similar in shape, cam 31 having a low portion 39 `and a high portion 48, while cam 38 has a low portion 4| and a high portion 42. Low portions 39 and 4| are preferably of the same radius and extent, and high portions 48 and 42 are of similar radius and extent, with portions 48 and 42 being angularly displaced a, slight amount, as best shown in Figure 2. Cams 31 and 38 are so arranged that cam 31 coacts with follower portion 23 and cam 38 coacts with follower portion 22. Further, as best shown in Figure 2, cams 31 and 38 are so proportioned that when high portion 48 of cam 31 engages follower portion 23 to tip the switch |4 as shown, low portion 4| of cam 38 engages follower portion 22 to prevent further tipping of switch I4 in the same direction. Likewise, upon a reverse operation of switch I4 by cam shaft 33 and cams 31 and 38, high portion 42 of cam 38 will then engage follower 22 and low portion 39 of cam 31 will engage follower portion 23 to hold switch I4 and its follower member |6 positively. Cam assemblies 36 are secured to shaft 33 by set screws 34 and are so arranged that the load switches carried by the follower member I6 will be operated in a desired sequence upon rotation of shaft 33.

Cam shaft 33 is biased in a switch opening position, counterclockwise in Figure 2 or clockwise in Figure 4, by tension spring means 26 attached to chassis I8 (at a point not shown) and to a lever arm I 9 which is secured to shaft 33. (See Fig. l.) A heat motor 58, shown in Figures 2, 4 and 5, is attached to the back portion of chassis I8 and is arranged to be connected by links 62 and 64 to crank pin 52 carried by a crank arm 53 attached to shaft 33.

Heat motor 58 comprises a pair of spaced bimetal strips 54 and 55 having a heater element 56 disposed between them. At one end, the bimetal strips are securely anchored to a stationary block 61, and the other ends of the strips are secured together by a pin 58, provision being made for slight movement of one strip relative to the other. A pivot pin 68, secured by a bracket 6I to the end of the bimetal strip 54, serves to connect the heat motor 58 to link 62. As shown in the drawings, the heat motor 58 is in its normal cold position andv is arranged to move link 62, to the right in Figure 4 or upwardly in Figure 5, when the heating element 56 is suiiiciently energized. The energization of heating element 56 of motor 58 is controlled by a balanced relay |45, preferably of the sort disclosed in Gille Patent No. 2,169,141, issued August 8, 1939, although any relay capable of controlling a circuit in response to variations' in the balance of a control network circuit may be used. As shown in Figure 7, relay |45 includes a switch arm |94, a contact |95 engageable thereby, and opposed windings |83 and |98.

Links 62 and 64 are pivotally connected at 65 and spring 66 is arranged to bias 64 clockwise relative to 62, the relative rotation of these links being limited by pin 61 in member 62 coacting with an opening 68 in the right end portion of link 64. Links 62 and 64 are pivotally connected so that link 64 can remain substantially horizontal as it is moved up or down, as in the following description.

Link 64 has a notch 18 near its left end, the notch being terminated on its left side by an abutment face 1|. Abutment face 1| is adapted to engage crank pin 52 when link member 64 is moved upwardly a suiiicient distance, as will be described. A pin 12, located to the left of abutment face 1| in link member 64, is arranged to engage surface 15 of a lever 13, said lever 13 being pivoted at 14 to bracket members |82. Lever 13 includes a slot 16 which coacts with a stationary pin 11 to limit the pivotal movement of the same and also includes a switch operating portion 18. Portion 18 of lever 13 engages a slot 88 in a pivoted lever 19 in a manner to open the contacts of a mercury switch II2 carried bylever 19 when pin 12 engages surface 15 and causes clockwise rotation of 13, and to close the contacts of said switch when pin 12 disengages surface 15.

A second switch operating lever 8| isl pivotally mounted on pin 11 and includes a switch operating portion 82, a horizontal pin engaging surface 83 and a notch 84. Lever portion 82 engages a pivoted switch carrying lever 85 in a manner to open the contacts of mercury switch carried by lever 85 when lever 8| is rotated clockwise and to close the contacts of the same when 8| is rotated, or permitted to rotate, counterclockwise. Switch |I2 is used to control solenoid apparatus 93 and switch controls the heater element 56 and control circuits, to be described, as the only object of switch ||2 is to deenergize the solenoid when it is not needed, this switch can be eliminated if desired.

A plunger mechanism including a top pin 9| and a bottom pin 92 is arranged in straddling relation to link 64 and is operated by solenoid apparatus 93 so that when the solenoid is energized, plunger mechanism 98 is pulled upwardly, pin 92 engages the bottom of link 64 and moves it upwardly and thus moves abutment face 1| into a position to engage crank pin 52 upon movement of link 64 to the right (Figure 4). Pin 9| is located so that when the solenoid is deenergized and the plunger mechanism is permitted to fall, pin 9| can push lever 64 downwardly to disengage face 1| from crank pin 52.` To be moresure that face 1| will be disengaged from crank pin 52, a lever 95 is pivoted on crank pin 52 and has a short pin 96 secured thereto and so arranged that when the lever 95 is in the position shown, the bottom portion of pin 96 is below crank pin 52 but when lever 95 is raised by bottom pin 92 of plunger mechanism 98, pin 96 is raised above crank pin 52. A stop 91 limits the down.- ward movement of lever 95 relative to link 64. A link |8| is pivotally attached to pin 92 of plunger mechanism 98 and is also pivotally secured to pin 'Il in brackets |82, link |8| having the sole purpose of guiding plunger mechanism 98 and preventing twisting thereof. A link |84 is pivotally connected at |85 to crank member 53 and includes a slot |86 for coacting with pivot pin 14 to limit the angular rotation of shaft 33, rotation being limited to about 60 in the present instance. While any suitable solenoid or similar electromagnetic apparatus may be used in the present controller, the solenoid structure disclosed in Gille Patent 2,114,961, issued April 19, 1938, is quite satisfactory.

In addition to the cam assemblies 36 adjusted by shaft 33, potentiometers ||'4 and ||5 are also adjusted thereby, potentiometer ||4 being connected to relay |45 for functioning as a follow up potentiometer in the control circuit, to be described, and the other potentiometer being available for controlling other apparatus if desired, its connections being identified as W, R and B in Figure 7. Potentiometer ||4 includes a wiper ||8 attached to shaft 33 and movable over a resistor I |1.

It is preferable that the control circuit above referred to be of low voltage; hence, a transformer |40 is provided, transformer |40 having a line voltage primary winding |10 and a low voltage secondary winding |14.

In the normal use of the present controller, a proportioning thermostat |41 is arranged to respond to the temperature of the space being controlled. This thermostat includes a resistor |48 and a wiper |49 adjustable over the resistor by temperature responsive bellows |50 acting in opposition to a spring |5|. This is a conventional thermostat for proportioning control and is shown in greater detail in Cunningham Patent 2,041,050 issued May 19, 1936. In this thermostat, the resistor wiper |49 is adjusted to the upper extreme of resistor |48 when the room temperature is relatively high and is adjusted to the bottom portion of the resistor as the room temperature decreases.

In addition to thermostat |41, a limit controller |52 is generally provided in a heating system and comprises a thermally responsive element |53 arranged to operate a mercury switch |54 or the like, to open circuit position upon the attainment of an undesirably high temperature in some portion of the heating system, as in the bonnet portion of the furnace which contains thek heating elements |51, |58, |59, |60 and so on, shown in Figure 7.

To facilitate connecting heater elements |51, |58, |59 etc. to load switches I3, |4, |5 and others, a terminal block is mounted on chassis I0 and the leads from the respective switches are attached to this block. One of the leads of ealch load switch, such as 2 0 of switch |4, is connected to a terminal structure comprising a bolt |2|, nut |22, connector |23 of lead 2|0, and a pedestal nut |24 which clamps connector |23 to bolt |2|. The other lead of each switch, such as 205 of switch I4, is connected by a suitable bus bar to a terminal |30. A fuse block |32 is superimposed on terminal block |20 and carries suillcient fuses to fuse both sides of the circuitscontrolled by the aforesaid load switches. Bus bar |33 is connected to the left end on each of the smaller fuses |31 while bus bar |34 is suitably connected to the right end of each of larger fuses |38, bus bars |33 and |34 being connected to power supply lines |35 and |36, respectively. The inner end of each of the fuses is secured to a flexible bus bar |39 which is bolted, through suitable openings in fuse block |32, to the top portion of its respective pedestal nut |24. With this arrangement, all the connections with the fuses in the fuse block are available from the top side of the block and, because of the flexibility of bus connections |39, a good electrical contact is had with each of the pedestal nuts, even though they may be slightly out of alignment and some higher or lower than others. Obviously, the necessary plain the present apparatus, the following dei scription of its operation is referred to.

Operation Assuming that line wires l| and |36 are en-v ergized, transformer |40 is energized by the circuit: line wire |35, bus bar |33, fuse |31, wire |1|, primary winding |10 of transformer |40, wire |12, fuse |38, bus bar |34, and line wire |36. With transformer |40 energized, a control circuit for the present device is energized as follows: secondary winding |14 of transformer |40, wire |15, wire |16, wire |11, switch |54 of safety limit device |53, wire |18, wire |19, switch wire |80, wire |8|, wiper ||8, wire |82, winding |83 of relay |45, wire |84, wire |85, resistor |48, wiper |49, wire |86, wire |81, and wire |88 back to secondary winding |14. In addition to the circuit described, it is noted that a parallel circuit from wiper ||6 exists as follows: wiper |6, resistor ||1, wire |89, winding |90 of relay |45, wire |9|, wire |92, and wiper |49. Thus, the voltage applied to wipers ||6 and |49 is divided by two parallel paths, one of the paths including resistor ||1 and relay winding |90 and the other path including resistor |48 and winding |83. As windings |83 and |90 have equal resistances, and as the resistance values of resistors ||1 and |48 are likewise equal, it follows that the current flow through each of the parallel branches is uniform,

` relay remains in a state of balance and its contact arm |94 is disengaged from contact |95.

Should the temperature of the room in which thermostat |41 is located now decrease a predetermined amount, spring |5| is able to force a retraction of bellows |50 and move wiper |49 downwardly across resistor |48 in accordance with the temperature drop. As wiper |49 moves Vformer |40, wire |15, wire |16, wire |11, switch |54, wire |18, wire |19, switch wire |80, wire |96, switch arm |94, contact |95, wire |91, heating element 56, wire |98, and wire |88 back to the secondary winding 14.

The energizing of heating element 56 causes heat motor 50 to start operating toward the back of chassis |0 (upwardly in Fig. 5). Referring to Figure 4, it is noted that movement of heat motor 50 to the right causes a similar shifting of,

links 62 and 64 to the right. The first effect of this movement is to move pin 12 from engagement with face 15 of lever 13 which permits switch ||2, by its own weight, to tip to a circuit closing position.v Closing of switch ||2, referring again to Figure '1, causes solenoid apparatus 93 to be energized by the circuit: secondary winding |14, wire |15, wire |16, wire |11, switch |54,wire |18, wire |19, switch wire |99, switch ||2, wire 200, winding 20| of solenoid apparatus 93, wire 202, and wire |88 back to the secondary winding |14. The energizing of solenoid 93, referring again to Figure 4, causes plunger mechanism 90 to be moved upwardly, thus bringing pin 92 into engagement with link member 64 and pulling it upwardly. Moving link member 64 upwardly brings abutment face 1| of notch 10 into engaging relation with crank pin 52. After abutment 1| of notch 10 engages crank pin 52, the effort requiredl to cause shaft 33 to rotate causes links 82 and 64 toV straighten out at pivot 65, causing link 64 to be liftedoi of pin 92, thereby relieving the solenoid of the effort required to hold link 64 upward and in operative engagement with pin 52. In addition, the straightening of links 62 and 64 provides enough clearance above pin 92 in its raised position to accommodate the slight lowering of link 64 due to rotation of crank arm 53, thereby preventing the solenoid from being pulled olf its seat. Motion of links 64 and 62 to the right obviously causes a counterclockwise rotation, in Figure 4, of shaft 33. Counterclockwise motion of cam shaft 33, clockwise in Figures 2 and 3, causes a movement oi' wiper ||6 across resistor II1 in a direction (upwardly in Fig. '1) to equalize the resistances in the two branches of the circuit controlling relay |45. At the same time, referring to Figure 2, clockwise rotation of cam shaft 33 results in high portion 42 of cam 38 engaging follower 22 in a direction to rotate follower member |6 in a counterclockwise direction for closing the contacts of switch I4. With high portion 42 in full engagement with follower 22, follower 23 then engages low portion 39 of cam 31 and switch I4 istilted in a manner to close its contacts.

Assuming that the switches I3 and I4 are ad,- .iusted to be simultaneously operated and vswitch I5 is adjusted to be operated upon a few degrees more rotation in the same direction, it is seen that the closing of switches I3 and I4 energizes heater element |51 by the circuit: line wire |35, bus bar |33, fuse |31, lead 2|0, switch I4, lead 205, wire 206, heater element |51, wire 201, lead 208, switch I3, lead 209, fuse |38, bus bar |34, and line wire |36. The few degrees furtherrotation referred to, which causes a closing of switch I5, then lcauses the energizing of heater element |58 by the circuit: line wire |35, bus bar |33, fuse |31, lead 2| I, switch I5, lead 2I2, wire 2|3, heater element |58, wire 2|4, wire 201, lead 208, switch I3, lead 209, fuse |38, bus bar |34 and line wire |36.

While movement of heat motor 50 has caused an operation of switches I3, I4 and I5 in the manner described, a similar movement of wiper |I6 has been taking place along resistor I|1 in a direction to balance the flow of current through relay windings |83 and |93. When this balancing takes place, arm |94 disengages contact |95, thereby deenergizing heater element 56. Upon heater element 56 being deenergized,`the bimetal of heat motor 50 immediately starts cooling and thus permits a movement of shaft 33 in a reverse direction due to the tension of spring 26. However, a reverse operation of shaft 33 due to the effect of spring 26 causes a similar movement of wiper II6 across resistor ||1 which results in unbaiancing the iiow of current through windings |83 and |90 of relay |45 so that added current again ilows through winding |83 and causes arm |94 to engage contact |95 and thus reestablish the current supply to heater element 56. The normal operation of the heat motor thus requires alternate heating and cooling with enough movement due to the heating to cause the follow-up potentiometer to balance the circuits through relay |45 and with the cooling of the heat motor progressing far enough to cause suillcient movement of the follow-up potentiometer I4 to again unbalance the circuit through the said relay. By

scribed.

enough that the main load switches will normally not be operated bythe hunting movement alone.

Assuming .that the temperature fall in the space wherein thermostat |41 is located was suf' flcient to bring on heater elements |51 and |58 to thus add heat to the space, but that the temperature in the space continues to drop due to the heat from elements |51 and |58 being inadequate, this results in a further contraction of bellows |50 and a consequent further movement of wiper` |49 downwardly across resistor |48. -This will of course, in a manner previously related, unbalance relay |45 in a direction to cause fur. ther heating of element 56 and will result in rotation of shaft 33 suflicient to effect a rebalancing of the control network in the manner above de- This additional movement will. of course, result in closing more of the'load switches in sequence and thus bring on more heat as the load requires. Should the temperature in the space to which thermostat |41 responds be sufficiently low as to cause movement of wiper |49 to the bottom of resistor |48, the circuit through I relay |45 would remain unbalanced until wiper ||6 advanced to the top of resistor ||1 (Fig. 7). this requiring the full permissible movement of cam shaft 33 and a closing of all of the switches controlled thereby. This represents the full load position of the controller.

A rise in temperature of the space results in an expansion of bellows |50 and an overpowering by the same of spring I5| to thus force wiper |43 upwardly across resistor 48 with the effect of unbalancing the network circuit including relay |45 so that heat motor 50 is permitted to cool suiiiciently to advance wiper ||6 downwardly across resistor I1 to rebalance the circuit. Con-` sequent movement of shaft 33 causes a sequential opening of the load switches and thus decreases the heat supplied to the space.

If, during the operation of the controller and the heating elements controlled thereby, something should cause an overheating of the furnace in which the heating elements |51, |58 etc. are located, limit device |53 operates to open the contacts of switch |54 and the load switches are all immediately opened for the opening of switch |54 deenergizes the control circuits of the controller including solenoid 93. When solenoid 93 is deenergized, plunger mechanism 90 drops by its own weight and pin 9| engages the top side of pry lever 95and forces it downwardly. With lever 95 being forced downwardly, it rotates about crank pin 52 so that pin 96 engages the bottom of notch 10 in a manner to pry link member 64 downwardly, this breaking the engagement of abutment face 1I with crank pin 52. Pin 9|l continues downwardly until it encounters the upper portion of link member 64 and directly acts against said member to force it downwardly. As soon as abutment face 1| of link 64 clears crank pin 52, spring 26 is enabled to rotate cam shaft 33 in a switch opening direction, to the full extent of travel permitted by limit link |04. This opens all of the load switches immediately. In addition, with link 64 being moved downwardly by plunger apparatus 90, pin 12 engages the upper surface 83 of lever 8| and rotates it clockwise to thus operate switch |I| to open its contacts. seen in Figure '1, even if the switch |54 of safety limit device |53 should vnow close, the control As will be apparatus cannot be reenergiacd for switch III is in series with switch I and all oi' the control circuits are also energized through switch III which is now open. Therefore, even if the temperature in the furnace, or other dangerous location, drops to a safe value, the heating load cannot be put back on the line because the load switches are all open and link member 6I is disengaged from crank pin 52. As heater element ll remains deenergized because of switch III being opened, heat motor 50 continues to cool and to advance, in Figure 4, to the left, thus moving link 6l to the left. Upon link member Il moving far enough to the left that pin 12 slides of! of suri'ace 8l and into registry with notch 84 of lever 8|, lever 8| is then caused to rotate counterclockwise by the unbalanced weight of switch IH which moves in a direction to close its contacts. Closing of the contacts of switch III assuming that pin 12 has not yet engaged surface 15 and that switch Il! therefore remains closed, then causes the control circuit iirst described in this description to be reestablished; solenoid 93 is reenergized by a circuit previously traced; hence, Iplunger mechanism 90 is pulled upwardly and forces abutment face 1| into engagement with crank pin 52. The reestablishment of a circuit to heater element 5i permits it to again cause heat motor 50 to bias in a direction to close the load switches and thus energize the heating elements for the space to an extent depending upon the load condition as determined by thermostat |41.

Because of the normal delay in movement of a heat motor and the sequential arrangement of the load switches, load is imposed on the electrical supply line in relatively small and spaced increments and thus avoids a sudden overloading of the line. Likewise, after a limit switch operation, the large load that may have been connected to the supply line at the time of the operation cannot be imposed on the line at one.

time, due to the operation Just described, and the load can be reestablished only by starting at the beginning and building it up by the predetermined increments.

Likewise, in the event of a power failure, the deenergizing of solenoid 93 causes plunger mechanism 80 to move link member 84 out of engagement with crank pin 52 and permit the spring 26 to open all of the load switches immediately. Then, as described under the limit switch operation, the heat motor must be cooled to an initial position before switch III can be closed and permit a reestablishment of the control circuit and then cause the operation, in the manner above described, of the load switches suillciently to meet the demands. This feature of immediately opening all the line switches upon power failure, or limit switch action, and permitting reestablishment of the load only upon a delay and by predetermined increments is of particular importance where a number of house heating loads are connected to a power supply line, for the immediate reestablishment of the full connected load of many houses to a power supply line after a power failure may make it diilicult to reestablish the power supply.

This disclosure is intended to be illustrative only and, as many substitutions and equivalents will be readily apparent to those skilled in the art, the scope of this invention is to be determined only by the appended claims.

I claim as my invention:

1. A step controller comprising, in combinasaid base portion forming a groove through which said shaft extends, securing means extending between said sidewalls and disposed in one of said circumferential grooves and main switch means operable by said follower means; a plurality of main switch terminal means; a plurality of fuses, means superimposing said fuses over said terminal means and means connecting said fuses to said switches; a cam shaft disposed adjacent said iirst shaft and having a plurality of pairs of cams so arranged that one ofthe cams of a pair is engageable with one of said cam engaging portions and the other cam of the pair is engageable with the other cam engaging portion, each of said cams having a high and a low portion, said high and low portions being so proportioned and arranged that a high cam portion always engages one follower portion while the low portion of the other cam of the pair engages the other follower portion; means for biasing said cam shaft in a switch opening direction; a crank pin attached to said cam shaft; bimetal heat motor means; link means for connecting said heat motor to said crank pin; said link means including relatively rotatable members connected for limited rotative movement relative to each other, spring means for biasing said members in one direction, one oi' said members being pivotally attached to said heat motor and the other of said members having a notch means for engaging said crank pin; solenoid actuated means for moving said link means so that said notch means may engage or disengage said crank pin; pivoted lever means also actuable by said solenoid means for assisting in disengaging the said link means from said crank pin; pin means carried by said link means; a normally closed switch means, means engageable by said link pin means when said link means is in an extremeposition for opening said normally closed switch means; a normally open switch means and means engageable by said link pin means upon a predetermined movement of said link means when said link means is disengaged from said crank pin for closing said normally open switch means; means connecting said normally open and said normally closed switch means in controlling relation with said solenoid means; balanced relay means for controlling the energization of said heat motor; follow-up means operable by said cam shaft, and means connecting said follow-up means in voltage dividing relation to said relay means.

2. In a control mechanism, a member to. be moved from an initial biased position to an adva'iced position against its bias, an actuator movable from an initial position to an advanced position and having an engaged condition in which it actuates said member and a disengaged condition in which said member may move to its initial biased position independently of said actuator, electromagnetic means for placing said actuator in its engaged condition when energized and which releases said actuator to its disengaged condition when deenergized, a switch in circuit with said electromagnetic means, and connections between said actuator and switch for opening the switch upon the actuator assuming u its disengaged condition while said actuator is i Il out of its initial position and for closing said switch when said actuator moves back to its initial position while remaining in its disengaged condition, whereby upon failure of electrical power while said member has been advanced against its bias from its initial position by said actuator, the actuator will assume its disengaged condition allowing said member to immediately return to its biased initial position and said electromagnetic means will remain deenergized even though electrical power is resumed and .until said actuator returns to its initial position.

,to connect said motor means to the actuating means when said electromagnetic means is energized and to detach said connecting means when deenergized, said linkage being arranged to straighten out and to move out of engagement with said electromagnetic means when force is applied to said connecting means by said motor means.

4. In`a control device, in combination, a movable actuating means, a motor means, a plural member linkage means for connecting said motor means to said actuating means, means for biasing said linkage out of alignment, and electromagnetic means for moving said linkage means into operative relation with said actuating means, said linkage being arranged to straighten out and to move out of` engagement with said electromagnetic means when force is applied to saidv said actuating means and force is exerted byv said motor means.

6. In a control device, a plurality of energy controlling switch means operable in sequence from one position to another, motor means, means including clutch means for connecting said motor means in operative relation to said switch means,

means for biasing said switch means to a position considered safe,' and means requiring energization for operating said clutch means in a manner to render said connecting means effective, said clutch operating means operating to disconnect said motor means from said switch means when deenergized.

7. A controller comprising,'in combination, a shaft having spaced transverse grooves therein, a plurality of cam follower means pivotally mounted on said shaft and having means extending into said grooves to maintain said follower means in spaced relation, cam means arranged to coact with said follower means, motor means, means including clutch mechanism for connecting said motor means in operative relation to said cam means, means for biasing said cam means in one direction, electrically con- *l trolled means for controlling said clutch mechal2 nism, andmeans operable as a function of the position of said connecting means for controlling said clutch mechanism.

8. In a control device, shaft means having a transverse .groove therein; switch carrying means having a base portion, spaced sidewall portions. spaced tongues turned inwardly from said sidewall portions, said tongues and said base por-A tions being arranged in substantial abutting relation with said shaft means, and means extending between said sidewall portions and into said transverse groove for holding said follower means on said shaft in a` manner to permit at least limited rotation of said switch carrying means relative to said shaft; switch means attached to said carrying means; and means for actuating said carrying means.

9. In control apparatus, a driven member to Abe moved from an initial position to other posiengaged condition in which said driven member may move to its initial position because of said biasing means and independently of said actuator.

member, electromagnetic means for placing said actuator member in its engaged condition when energized and which releases said actuator member to its disengaged condition when deenergized, a switch in circuit with said electromagnetic means, means for operating said switch to open circuit position upon the actuator member assuming its disengaged condition while it is still away from its initial position and for closing said switch when said actuator member moves back to its initial position while remaining in its disengaged condition, and means actuated by said electromagnetic means for forcing said actuator member out of engagement with said driven member when said electromagnetic means is deenergized.

10. A control system comprising, in combination, condition changing means, a controller for said condition changing means, heat motor means for actuating said controller, potentiometer means actuated by said controller means, condition responsive potentiometer means, balanced relay means having opposed windings and a. switch means, circuit means connecting said switch means in on-oi control of said heat motor means,

, and conductor means connecting Iboth of said potentiometers and said relay windings to form a voltage dividing network capable of controlling said relay means.

11. In control apparatus, a driven member to be moved from an initial position to other positions, means for biasing said member to said initial position, an actuator member movable from an initial position to other positions, said actuator member having an engaged condition in ywhich it may actuate said driven member and a disengaged condition in which said driven and for closing said switch .when said actuator member moves back to its initial position while remaining in its disengaged condition, and means for disengaging said actuator member from said electromagnetic means when force is applied through said actuator member to said driven member.

12. A multiple switch control device comprising, in combination, a plurality of switches, means for actuating said switches from an off" position to various on" positions, motor means, holding means operable against a bias for detachably connecting said motor means in operative relation to said actuating means, means for biasing said switch actuating means to the "oiT position, and means forming part of said holding means for disconnecting said motor means from said actuating means in the event of a power failure.

13. A control device including a motor means, means arranged to be driven by said motor means, means including clutch means for connecting said motor means to said driven means, electromagnetic means for controlling said clutch means, and switch means controlled by said connecting means for preventing an initial energization of said electromagnetic means unless said connecting means is in a predetermined position.

14. Control apparatus comprising, in combination, motor means, a driven mechanical means, means including a clutch means for connecting said motor means to said driven means, electromagnetic means for controlling said clutch means, circuit means for energizing said motor means, said clutch means being operable `to connect said motor means'in driving relation to said driven means only when said electromagnetic means is energized, and means controlled by said connecting means for preventing energization of said motor means unless the clutch means is engaged or the connecting means is in a predetermined position.

15. A control device, comprising, in combination, actuating means, heat motor means movable in one direction upon being energized and movable in the other direction upon being deenerlined, means for biasing said actuating means in one direction, means for detachably connectim said motor means to said actuating means,

eticmeans for controlling said connectlonmeansinamannertoconnectthemotor means to the actuating means when said electromagnetic meansis energized and to detach said connecting means when deenergiaed, and switch ymeans operable by said connecting means for controlling the tion of said electromagnetic means.

18. Control apparatus comprising, in combinatien, a control device, said device including an actuating means, a motor means, electromagnetic eonh'olled means for connecting said motor .c 2,169,039

14 means to said actuating means when energized, spring means for biasing said actuating means to a predetermined position, condition responsive means for controlling said motor means, and an additional condition responsive means for controlling the energization of said electromagnetic means.

17. A multiple switch control device comprising, in combination, a plurality of switches, means for actuating said switches from an oil position to various on positions, motor means, electrically controlled means for detachably connecting said motor means in operative relation to said actuating means for operating said switch means to on positions, spring means for biasing said switch means to oiT position, said electrically controlled means causing a detaching of said connecting means upon being deenergized for permitting said spring means to operate said switches to oii position, and means preventing reenergization of said electrically controlled means until said motor means moves to a position in accordance with the 011 position of the said switches.

18. A control device comprising, in combination, actuating means, heat motor means for urging said actuating means in one direction when energized, spring means for urging said actuating means in an opposite direction, relay means for controlling the energization of said heat motor in an on-off manner, and voltage dividing follow-up means operated by said actuating means and connected in controlling relation with said relay.

19. A step controller comprising a plurality of switches, means for actuating said switches in a predetermined sequence from an initial position, motor means, means for detachably connecting said motor means to said actuating means for operation thereof, electrical means for controlling said detachable connection means, and means requiring said switch means to be in the initial position of the sequence before said detachable connection means can be effectively lcontrolled to place the motor means in operative relation to the switch actuating means.

ALEXANDER J. BIELBKI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,817,635 McCabe Aug. 4, 1931v 1,942,587 Whitman Jan. 9, 1934 2,026,373 Bush Dec. 31. 1935 2,032,658 Gille Mar. 3, 1936 Defandorf et al. Aus. 8, 1939 

